Due to ever tighter emission control values, emission control on internal combustion engines is of great importance. The use of exhaust control system catalytic converters is indispensable for the reduction of pollutant emissions both on spark-ignition engines and on diesel engines. In addition modern internal combustion engines have injection control systems which enable a precise control of the composition of the combustion mixture and thus guarantee the best possible pollution limitation. An essential component of the injection control system is the lambda sensor fitted in the exhaust-gas tract of the internal combustion engine. On diesel engines and on spark-ignition engines, with which stratified-charged operation and/or lean operation is possible, linear lambda sensors, which are also known as wideband lambda sensors, are used. The output signal of these lambda sensors is, however, subject to errors, for example due to contamination, ageing or amplification errors.
A possible method of compensating for these inaccuracies is, for example, disclosed in DE 198 42 425 A1. According to this, the lambda sensor is calibrated during a fuel cut-off overrun phase of the internal combustion engine while the internal combustion engine is rotating with the injection switched off. During this fuel cut-off overrun phase, the output value of the lambda sensor is compared with a predetermined reference value for pure air under standard conditions and a correction factor is determined from any deviation. However, this method cannot also compensate for all inaccuracies of the lambda sensor.